Optical storage medium with optically detectable marks

ABSTRACT

Optically detectable marks readable by a wide range of optical systems are included on an optical storage medium. Among other uses, the marks may be used to determine the type of the optical storage medium in an optical device capable of reading multiple types of optical storage media.

FIELD OF THE INVENTION

The present invention relates generally to optical storage technologyand more specifically to optical devices capable of reading multipletypes of optical storage media.

BACKGROUND OF THE INVENTION

Optical storage technology has evolved from the compact disc (CD) andlaser disc (LD) to far denser types such as digital versatile disc (DVD)and blue laser formats such as Blu-ray. Many optical devices capable ofreading the newer, denser media types are also designed to read lowercapacity media types such as CDs. This backward compatibility comes at aprice, however, because the low- and high-density media types requireoptical systems having different parameters such as numerical aperture(NA) and laser diode wavelength (λ). An optical device capable ofreading multiple media types must, therefore, adjust (focus) the variousoptical systems (combinations of laser and optics) in succession untilit finds the correct one for a particular optical disc. In such opticaldevices, the start-up time increases with the number of optical storagemedia types supported.

It is thus apparent that there is a need in the art for an improvedindication to enhance the detection of the type of an optical storagemedium or other necessary information.

SUMMARY OF THE INVENTION

Methods for rendering detectable and determining the type of an opticalstorage medium or other necessary information are provided. An opticalstorage medium and an optical device for carrying out the methods arealso provided.

Other aspects and advantages of the present invention will becomeapparent from the following detailed description, taken in conjunctionwith the accompanying drawings, illustrating by way of example theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an illustration showing some areas of an optical storagemedium in accordance with an illustrative embodiment of the invention

FIG. 1B is an illustration of a cross section of an optical storagemedium in accordance with an illustrative embodiment of the invention.

FIG. 1C is an illustration showing marked areas (pits) and lands(unmarked areas) on a data layer of an optical storage medium inaccordance with an illustrative embodiment of the invention.

FIG. 2A is an illustration of optically detectable marks on an opticalstorage medium in accordance with an illustrative embodiment of theinvention.

FIG. 2B is an illustration of optically detectable marks on an opticalstorage medium in accordance with another illustrative embodiment of theinvention.

FIGS. 2C-2F are illustrations of different approaches to formingoptically detectable marks on an optical storage medium in accordancewith various illustrative embodiments of the invention.

FIG. 2G is an illustration showing, in accordance with variousillustrative embodiments of the invention, that the different approachesshown in FIGS. 2C-2G produce an equivalent optical system output.

FIG. 2H is an illustration showing various layers of an optical storagemedium on which optically detectable marks may be placed in accordancewith various illustrative embodiments of the invention.

FIG. 3 is a flowchart of a method for rendering detectable the type ofan optical storage medium in accordance with an illustrative embodimentof the invention.

FIG. 4 is a functional block diagram of an optical device in accordancewith an illustrative embodiment of the invention.

FIG. 5 is a flowchart of the operation of the optical device shown inFIG. 4 in accordance with an illustrative embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

One or more optically detectable marks readable under sub-optimal focusand radial position conditions by a wide range of optical systems havingdifferent parameters such as numerical aperture (NA) and laser diodewavelength (λ) may be included on an optical storage medium. Among otheruses, such marks allow the type of an optical storage medium to bedetermined directly, without the delay incurred in a trial-and-errorapproach. Some ways in which such marks may be created and used arediscussed in the balance of this detailed description. In addition tocommunicating the type of an optical storage medium, such opticallydetectable marks may be used to convey other necessary information.Throughout this description, “optical storage medium” denotes any kindof read-only, writable, or re-writable optical storage technology,including, but not limited, to compact discs (CDs), digital versatilediscs (DVDs), Blu-ray discs, and advanced optical discs (AODs).

FIG. 1A is an illustration showing some areas of an optical storagemedium 100 in accordance with an illustrative embodiment of theinvention. In this particular embodiment, optical storage medium 100comprises a circular optical disc. Optical storage medium 100 includes ahole 105, clamping area 110, lead-in area 115, user-data area 120, andlead-out area 125. User-data area 120 stores digital information such asaudio, video, computer files, or a combination thereof. Lead-in area 115and lead-out area 125 are part of the non-user-data area of opticalstorage medium 100. Lead-in area 115 may, for example, store informationabout the disc's contents. Lead-out area 125 may, for example, signal toan optical device that the end of the data stored on the disc has beenreached.

FIG. 1B is an illustration of a cross section of optical storage medium100 in accordance with an illustrative embodiment of the invention.Optical storage medium 100 comprises at least one data layer 130surrounded by a protective layer 135 and a polycarbonate plasticsubstrate 140 having a surface 143. In general, optical storage medium100 may have one or more buried layers (layers beneath surface 143),which may be data layers 130 or non-data layers (not shown in FIG. 1B).Laser beam 145 focuses on data layer 130 as optical storage medium 100spins at a rate controlled by a spindle motor. Data layer 130 includes areflective metal coating, which allows the optical system of an opticaldevice to read encoded digital information by detecting the change inreflectivity as the disc spins beneath laser beam 145. The particulartype of optical storage medium 100 depicted in FIG. 1B is a read-onlyoptical disc such as a commercial CD, but other types of optical storagemedia 100 such as DVDs and writable or re-writable optical discs arealso comprised of a substrate and at least one data layer 130. Somenewer types of optical storage media 100 have two readable sides insteadof one (e.g., a two-sided DVD) and/or multiple data layers 130 per side(e.g., a dual-layer DVD).

FIG. 1C is an illustration of the marked areas (pits) 150 and unmarkedareas (lands) 155 on data layer 130 of optical storage medium 100 inaccordance with an illustrative embodiment of the invention. The pits150 and lands 155 depicted in FIG. 1C are associated with a data layer130 (e.g., video, audio, computer data, or a combination thereof) ofoptical storage medium 100. FIG. 1C is a top view of data layer 130 asseen from the laser side of optical storage medium 100. Also shown inFIG. 1C is the laser focus spot 160 that passes over the pits 150 andlands 155 as an optical device reads optical storage medium 100. Data istypically encoded on optical storage media using a non-return-to-zero(NRZ) code and either pulse-width modulation (PWM) or pulse-positionmodulation (PPM), although PWM is more common than PPM.

FIG. 2A is an illustration of optically detectable marks 210 on opticalstorage medium 100 in accordance with an illustrative embodiment of theinvention. In this embodiment, optical storage medium 100 comprises adisk-like body 205 and at least one optically detectable mark 210(“mark”) that is readable by a wide range of optical systems configuredfor different types of optical storage media. For example, marks 210 maybe read by an optical device configured for CDs, DVDs, Blu-ray discs,AODs, or other types of optical storage media. Marks 210 that areappropriately sized and spaced may be detected even though the laserbeam 145 of a given optical system cannot focus properly on a data layer130 of a particular optical storage medium 100 being identified due tooptical system issues or the lens being in a fixed position.Additionally, the radial size of marks 210 eliminates the need forradial tracking.

Marks 210 may be arranged and employed in a variety of ways. Forexample, as few as one optically detectable mark 210 may be included onoptical storage medium 100, or a number sufficient to form a partial orcomplete band around a circle concentric with the circumference ofoptical storage medium 100 may be included, as shown in FIG. 2A. Also,marks 210 may be uniformly spaced as in FIG. 2A or non-uniformly spaced.Further, marks 210 may be of uniform or non-uniform size. Finally, marks210 may be located in any non-user-data area of optical storage medium100, including lead-in and lead-out areas 115 and 125, respectively. Inthe illustrative embodiment shown in FIG. 2A, marks 210 are in lead-inarea 115 of optical storage medium 100. One use for marks 210 is toindicate the type (e.g., CD, DVD, etc.) of optical storage medium 100.For example, the spacing 215 between marks 210, the size (e.g., width220) of one or more marks 210, or a combination of the two may conveysuch information or other necessary information. Where the size of marks210 is employed, width 220, radial length, or both may be included inthe measurements.

In FIG. 2A, the size of marks 210 has been exaggerated for clarity. Inpractice, an acceptable size for marks 210 is determined primarily bythe NA and λ of the optical system and the allowed level of defocus orthe range of the radial position, as those skilled in the art willrecognize. Also, the spacing 215 between marks 210 may be madesufficient for the marks 210 to be detectable by an optical systemachieving a largest (worst-case) expected laser focus spot 160 with thecorresponding amount of spot aberration. In one embodiment, for example,marks 210 may be on the order of 1-3 mm in width, depending on whethermarks 210 are on the surface 143 of optical storage medium 100 or at aburied layer (e.g., a data layer 130 or a non-data buried layer)thereof. More will be said about ways in which marks 210 may be createdin a later portion of this description.

FIG. 2B is an illustration of an optical storage medium 100 inaccordance with another illustrative embodiment of the invention. FIG.2B illustrates that marks 210 may be uniform in width along an axiscoinciding with a radius of optical storage medium 100 instead of beingshaped like sectors of an annulus as in FIG. 2A. Other shapes arepossible and are all within the intended scope of the claimed invention.For example, marks 210 may be trapezoidal in shape. FIG. 2B furtherillustrates that marks 210 may be located in lead-out area 125 ofoptical storage medium 100 instead of lead-in area 115.

There are a variety of ways in which marks 210 may be included onoptical storage medium 100. In one embodiment, marks 210 may be embossedon a data layer 130 of optical storage medium 100 in a manner similar tothat in which digital data is stored on the medium. To ensure the marksare large enough in the radial direction, multiple spiral “tracks” maybe packed closely together. In this embodiment, marks 210 may be definedas either pits 150 or lands 155, and they may be represented andinterpreted using PWM, PPM, or any other suitable technique.

FIGS. 2C-2F illustrate different ways in which pits and lands may bearranged to form a sufficiently large mark 210 on optical storage medium100. In FIG. 2C, the tracks are spaced somewhat apart, and the landsforming mark 210 are radially aligned. In FIG. 2D, the tracks areadjoining, and the lands forming mark 210 are radially aligned. In FIG.2E, the tracks are spaced somewhat apart, and the lands forming mark 210are not radially aligned. In FIG. 2F, the tracks are adjoining, and thelands forming mark 210 are not radially aligned. FIG. 2G illustratesthat, no matter which of the approaches in FIGS. 2C-2F is employed, anoptical system of an optical device reading mark 210 produces anequivalent output signal 225, although some low-pass filtering of theoutput signal may be necessary to achieve the waveform shown in FIG. 2G.

In another embodiment, marks 210 may be screen printed on surface 143 ofoptical storage medium 100 or on some other surface of optical storagemedium 100, including a buried layer. An optical system may detect ascreen-printed mark 210 by measuring the drop in reflectivity along mark210. Instead of screen printing marks 210 on optical storage medium 100,an ink-jet process may be used. In yet another embodiment, a portion ofthe metal reflective coating of data layer 130 of optical storage medium100 may be ablated (evaporated away) by a high-power laser. Thoseskilled in the art will recognize that this technique is used in theburst-cutting area of read-only DVDs.

FIG. 2H summarizes that marks 210 may be located on surface 143, anon-data buried layer 230, or on one or more data layers 130 of opticalstorage medium 100. In some embodiments, non-data buried layer 230 maybe between two data layers 130.

FIG. 3 is a flowchart of a method for rendering detectable the type ofan optical storage medium 100 in accordance with an illustrativeembodiment of the invention. At 305, at least one mark 210 correspondingto the type of an optical storage medium 100 is selected. This selectionmay be based upon a prior mapping of various media types to the size(e.g., width 220) and/or their spacing 215 of marks 210, as explainedabove. For example, a complete band of marks 210 in the lead-in portionof optical storage medium 100 at a predetermined uniform spacing mayindicate a Blu-ray disc. At 310, the selected mark or marks 210 areincluded on optical storage medium 100, as explained above. At 315, theprocess terminates.

FIG. 4 is a functional block diagram of an optical device 400 inaccordance with an illustrative embodiment of the invention. Opticaldevice 400 may be any device capable of at least reading one or moretypes of optical storage media. For example, optical device 400 may be aCD device, a DVD device, a computer optical drive, or any similardevice. In FIG. 4, optical storage medium 100 is mounted or attached tospindle motor 405, which rotates optical storage medium 100. Sled motor410 positions optical pickup unit (OPU) 415 at the approximate radiusdetermined by optical system controller 420. OPU 415 contains anobjective lens 425 and the electromechanical means to position objectivelens 425 at the correct radial and vertical positions to focus laserbeam 145 to the appropriate spot size on optical storage medium 100.Additionally, OPU 415 contains a laser diode, photo detectors, andadditional optical components (not shown in FIG. 4) to create laser beam145 or read the reflected laser beam 145 from optical storage medium100. Interface electronics 430 converts signals between optical systemcontroller 420 and sled motor 410, OPU 415, and spindle motor 405between digital and analog formats. For the purposes of thisdescription, OPU 415, optical system controller 420, objective lens 425,and interface electronics 430 will be referred to collectively asoptical system 435.

Optical system controller 420 typically includes data decoding andformatting logic implemented as either hardware or firmware. Opticalsystem controller 420 may also contain logic (“mark interpretationlogic”) for interpreting marks 210. For example, optical systemcontroller 420 may contain logic for recognizing the type of opticalstorage medium 100 or other useful information conveyed by marks 210.Typically, information from optical system controller 420 is exchangedwith drive and host interface controller 440 using memory 445 via aninternal bus 450. Drive and host interface controller 440 maintainscommunication and exchanges user and system data for reading and writingoptical storage medium 100 with computer 455 via a physical connection460, such as IDE, SCSI, IEEE 1394 or USB. Information exchanged betweenoptical device 400 and computer 455 may be stored temporarily in memory445.

FIG. 5 is a flowchart of the operation of optical device 400 shown inFIG. 4 in accordance with an illustrative embodiment of the invention.After optical storage medium 100 is inserted and mounted in opticaldevice 400, optical system controller 420 causes sled motor 410 to moveOPU 415 to a specified radius, spindle motor 405 to rotate opticalstorage medium 100 at a specified angular velocity, and objective lens425 to move to a specified fixed position at 505. Marks 210 are sizedradially to allow for some degree of tolerance for the positionalaccuracy of optical system 435. At 510, the resulting laser beam 145 isreflected from optical storage medium 100 to the photo detectors in OPU415. At 515, the mark interpretation logic of optical system controller420 may interpret the information contained in at least one mark 210 andpass that information to the drive and host interface controller 440,which in turn communicates the information to computer 455. For example,optical system controller 420 may interpret the at least one mark 210 todetermine the type of optical storage medium 100. At 520, the processterminates.

The foregoing description of the present invention has been presentedfor the purposes of illustration and description. It is not intended tobe exhaustive or to limit the invention to the precise form disclosed,and other modifications and variations may be possible in light of theabove teachings. The embodiments were chosen and described in order tobest explain the principles of the invention and its practicalapplication to thereby enable others skilled in the art to best utilizethe invention in various embodiments and various modifications as aresuited to the particular use contemplated. It is intended that theappended claims be construed to include other alternative embodiments ofthe invention except insofar as limited by the prior art.

1. An optical storage medium, comprising: a disk-like body; and at leastone optically detectable mark on the disk-like body, the at least oneoptically detectable mark being readable by a plurality of differentoptical systems configured for different types of optical storage media.2. The optical storage medium of claim 1, wherein the at least oneoptically detectable mark is located on a buried layer of the opticalstorage medium.
 3. The optical storage medium of claim 2, wherein theburied layer is a non-data layer of the optical storage medium.
 4. Theoptical storage medium of claim 2, wherein the buried layer is a datalayer of the optical storage medium.
 5. The optical storage medium ofclaim 1, wherein the at least one optically detectable mark is locatedon a surface of the optical storage medium.
 6. The optical storagemedium of claim 1, wherein the at least one optically detectable mark islocated within a non-user-data area of the optical storage medium. 7.The optical storage medium of claim 6, wherein the non-user-data areacomprises a lead-in area of the optical storage medium.
 8. The opticalstorage medium of claim 6, wherein the non-user-data area comprises alead-out area of the optical storage medium.
 9. The optical storagemedium of claim 1, wherein the at least one optically detectable mark isuniform in width along an axis coinciding with a radius of the opticalstorage medium.
 10. The optical storage medium of claim 1, wherein theat least one optically detectable mark is shaped approximately like asector of an annulus.
 11. The optical storage medium of claim 1, whereinthe at least one optically detectable mark is trapezoidal in shape. 12.A method for determining the type of an optical storage medium,comprising: reading, from the optical storage medium using an opticalsystem, at least one optically detectable mark that is readable by aplurality of different optical systems configured for different types ofoptical storage media; and interpreting the at least one opticallydetectable mark to identify the type of the optical storage medium. 13.The method of claim 12, wherein the optical storage medium comprises acircular disc and the at least one optically detectable mark comprises aband of optically detectable marks disposed around a circle concentricwith the circumference of the optical storage medium.
 14. The method ofclaim 13, wherein the optically detectable marks comprising the band areuniformly spaced.
 15. The method of claim 13, wherein the opticallydetectable marks comprising the band are spaced sufficiently far apartto be detectable by an optical system achieving a predetermined largestexpected focus spot.
 16. The method of claim 13, wherein interpretingthe at least one optically detectable mark to identify the type of theoptical storage medium comprises measuring the spacing of the opticallydetectable marks comprising the band.
 17. The method of claim 12,wherein interpreting the at least one optically detectable mark toidentify the type of the optical storage medium comprises measuring atleast one dimension of the at least one optically detectable mark. 18.The method of claim 12, wherein the type comprises at least one of CD,DVD, Blu-ray, and AOD.
 19. A method for rendering detectable by anoptical system the type of an optical storage medium, comprising:selecting at least one optically detectable mark as corresponding to thetype of the optical storage medium, the at least one opticallydetectable mark being readable by a plurality of different opticalsystems configured for different types of optical storage media; andincluding, on the optical storage medium, the at least one opticallydetectable mark.
 20. The method of claim 19, wherein including, on theoptical storage medium, the at least one optically detectable markcomprises embossing the at least one optically detectable mark on aburied layer of the optical storage medium.
 21. The method of claim 19,wherein including, on the optical storage medium, the at least oneoptically detectable mark comprises screen printing the at least oneoptically detectable mark on at least one of an outer surface and aburied layer of the optical storage medium.
 22. The method of claim 19,wherein including, on the optical storage medium, the at least oneoptically detectable mark comprises ink-jet printing the at least oneoptically detectable mark on at least one of an outer surface and aburied layer of the optical storage medium.
 23. The method of claim 19,wherein including, on the optical storage medium, the at least oneoptically detectable mark comprises ablating a metallic layer of theoptical storage medium.
 24. The method of claim 19, wherein including,on the optical storage medium, the at least one optically detectablemark comprises representing the at least one optically detectable markusing pulse-width modulation.
 25. The method of claim 19, whereinincluding, on the optical storage medium, the at least one opticallydetectable mark comprises representing the at least one opticallydetectable mark using pulse-position modulation.
 26. The method of claim19, wherein the type comprises at least one of CD, DVD, Blu-ray, andAOD.
 27. An optical device, comprising: an optical system to read, froman optical storage medium, at least one optically detectable mark thatis readable by a plurality of different optical systems configured fordifferent types of optical storage media; and logic configured tointerpret the at least one optically detectable mark.
 28. The opticaldevice of claim 27, wherein the optical device comprises at least one ofa DVD device, a CD device, a Blu-ray device, an AOD device, and acomputer optical drive.
 29. An optical device, comprising: means forreading, from an optical storage medium, at least one opticallydetectable mark that is readable by a plurality of different opticalsystems configured for different types of optical storage media; andmeans for interpreting the at least one optically detectable mark.